London Irish kick off their campaign against Madejski Stadium visitors Edinburgh tomorrow, knowing they cannot afford to drop points at the outset in Pool One, a group that also includes Cardiff Blues and French challengers Racing Metro.

"If you want to progress out of the group stages in this competition you have to win your home games, starting tomorrow," Irish head coach Toby Booth said.

Leicester, struggling in the Aviva Premiership, begin another European season tomorrow, albeit on unfamiliar territory.

The Tigers tackle Pool Four underdogs Aironi at Stadio Brianteo in Monza, the 95th different venue to stage Heineken Cup rugby.

Geordan Murphy skippers a side showing three changes from the team held at home by Irish last weekend, with wing Niall Morris, centre Andy Forsyth and prop Dan Cole all starting.

Forsyth replaces Horacio Agulla, who suffered a hand injury in the Irish match and joins Mathew Tait, Manu Tuilagi, Anthony Allen and Billy Twelvetrees on Tigers' current list of absentees.

Holders Leinster, minus an injured Brian O'Driscoll, begin their title defence with a tricky assignment in Montpellier tomorrow, and skipper Leo Cullen admitted: "It will be a really tough opener.

"Montpellier had an unbelievable home record in the Top 14 last year, and they were within 10-15 minutes of beating Toulouse in the French final.

"It is almost a given that in the Heineken Cup you have to win your home games, so you ask yourself where you are going to pick up an away win.

"It is tough to see where that can come from, although we will have an opportunity straight away against Montpellier."

In tomorrow's other games, Pool One dark horses the Scarlets host Castres, Ulster entertain Pool Four opponents Clermont Auvergne and Pool Five heavyweights the Ospreys and Biarritz clash at Swansea's Liberty Stadium.

The Scarlets encounter sees a Heineken Cup debut for Wales wing George North, a World Cup star in New Zealand who returns to regional duties alongside colleagues like Stephen Jones and Scott Williams.

"I guess it is a bit strange that I have played in the World Cup and Six Nations for Wales, but not in the Heineken Cup," North said.

"I guess it's not the normal order to do things.

"But as a player you want to test yourself at every level, and this is the closest you can come to playing international standard without pulling on the national jersey.

"There is a great tradition in the competition for the Scarlets, and that is an inspiration to us all."